Figure 1.

The T cell response during acute and persistent antigen stimulation. For acute antigen stimulation, the expansion of Teff cells is followed by antigen clearance. After the antigen is cleared, the majority of antigen specific T cells die off, leaving a small number of Tmem cells. For persistent antigen stimulation, the antigen is not cleared leading to the differentiation of the Teff cells to an exhausted state. MPECs: memory precursor effector cells, Teff: effector T cells, Tmem: memory T cells. Original figure.